Michigan
State University Extension
Preserving
Food Safely - 01600601
10/13/97
Because both acid and heat are destructive to
chlorophyll, a bright green color is not to be expected in
pickles. During pickling, the magnesium atom in the center
of the chlorophyll molecule is replaced by two hydrogen
atoms to form pheophytin, an olive green pigment. While
the olive green color of pickles is not as attractive as the
natural green color, it is accepted as characteristic of
pickles.
If copper replaces magnesium in the chlorophyll
molecule, the pigment takes on a vivid green color.
Formerly copper kettles were used for cooking pickles in
order to impart a bright green color, but this practice is
not recommended. Some old-fashioned pickle recipes call for
using a "blue stone"--namely copper sulfate-- to give the
pickles a bright green color. We do not recommend this
practice because copper can be toxic if present in large
enough quantities.
